Method and means for protecting liquid-insulated electric apparatus



M. BUCH HOLZ METHOD AND MEANS FOR PROTECTING LIQUID INSULATED ELECTRIC APPARATUS Filed Sept. 15. 1922 6 I 72 van Z02" Patented Sept. 13, 1927.

UNITED. STATES PATENT OFFICE.

MAX BUGHHOLZ, DI CASSEL, GERMANY.

Application filed September 15, 1922, Serial No. 588,457, and in Germany September 26, 1821.

My invention has reference to a method and means for protecting electric apparatus operating in an insulating liquid, such as oil transformers, oil switches, grounding throttling coils, resistances and the like, and it is one of the important objects of my invention to provide a device of very simple construction and great reliability, and adapted to operate before extensive injuries to the apparatus to be protected can occur by sparking, overloading or other disturbances. My invention is particularly based on the fact that in the case of disturbances in the operation of the apparatus to be protected or in the case of sparking or other irregularities of operation, or whenever such irregularities are imminent, aswell as in the case of any ebullition or fermentation processes in the oil, servin as an insulating liquid, bubbles of gases of decomposition are formed which can operate protective means, for instance an electric contact, either a working or a closed contact, which is adapted to switch out of circuit the apparatus to be protected, or which will operate an alarm or annunciator device indicating the disturbance, or which is adapted to effect both kinds of operations. The gases formed by decomposition may influence the protective means in different ways. Thus, for instance, their upward pressure may be utilized,'or the variations of pressure caused by their generation in the insulating liquid, or the vibrations or concussions caused therein by their liberation may also be employed as an operating means, or they may be made to .act by the change of volume of the liquid incident upon their generation, or the electric changes caused thereby at the terminals of a sparking gap.

The protective device according to this invention may be arranged at different places, either in the interior of the main oil receptacle, or, in the case of transformers, in com ination with expansion vessels contained therein, or special spaces, tubes or similar. instrumentalities may be provided ada ted for thereception of the contacting devlces. The closing of the circuit may be effected both within as well as outside of the liquid.

The circuit to be controlled by the contacts referred to may excite either directly or by the medium of an'intermediate relay the releasing coil of an oil switch which interrupts the endangered circuit. In the case of apparatus the circuit of which does not include an 011 switch, as frequently occurs, for instance, in the cases of transformers mounted:

in the field at wide distances apart, other provision should be made for the purposes of this invention. Thus, for example, the

'closing of the contacts may be caused to operate a switch, a pawl, or an equivalent member adapted to establish an artificial or harmless short-circuit at the outside of the apparatus, so as to cause wire fuses or the like in series with the apparatus to be protected to be released.

The bubbles to be utilized for the actuation of the fuse or safety means are either products of decomposition or they constitute vapors of the liquid.

The invention will be more particularly pointed out and described with reference to the accompanying drawing illustrating by way of example an embodiment thereof in a conventional manner, and in elevation, In the drawing the transformer casing is indicated at a, while I; represents the core of the transformer with the windings c; d are the leading-in insulations for the conductors, e is the oil switch with the releasing coil f, and g is a source of current which upon the operation of the safety device, excites the coil,

releases the oil switch, and causes the switching out of the endangered piece of apparatus. In the form shown in the drawing by way of example the operation is effected eitherby the upward pressure of the gases or vapors generated or the device is made to respond to the impulse of the liquid or fluid caused thereb Below the surface of the oil a hood 7?. oats having a tubular neck m. Any gases or vapors liberated will accumulate in the neck, and force the inovably supported flap i upwards to such an extent that it touches the contact k which is rigidly secured to the hood h, thereby establishing the H circuit for the safety device. In other words, the bubbles of gas while unable to lift the relatively heavy hood, will easily lift the contact flap z'which can be balanced as desired and 50 per cent, or even less, of the bubbles will sutfice to lift it, the rest being allowed to. ass around the'flap.

Besides the orm of construction herein shown and described, the invention is susceptible of a variety of other modifications and forms of application of the princi le of. my invention all of which operate su stantially in a similar manner. The means of connecting the contacting device with the releasing circuit and the switching means are open to changes and alterations without any material importance for the operation of the apparatus according to my invention ,WhlCh in its broad aspects comprises the operation of safety devices for electric apparatus or the like, adapted for operation by vapors, fumes, gases or similar emanations liberated and expelled from the insulating medium,- and means adapted to be operatively infiuenced by such emanations, and connected to fuses or equivalent safety means, the instrumentalities shown and described in this specification as embodiments of these principles being susceptible of modifications without deviating from"the spirit of my invention as set forth in the claims.

The term protective circuit as used in the claims includes the main or any shunt circuit, in which the apparatus to be protected is inserted, as wellas any auxiliary circuit containing switching or signalling means or alarms or both.

In the claims the term gases is meant to comprise also vapors and fumes.

I claim:

1. Protective system for liquid insulated electric apparatus comprising a container and a supply of insulating liquid surrounding the apparatus to be protected, a protective means and means adapted to be operated by a product of decomposition occurring in the insulating liquid for actuating said protective means.

2. Protective system for liquid-insulated electric apparatus comprising a container and a supply of insulating liquid, surrounding the apparatus to be protected, a protectlve circuit and means adapted to be operated by a product of decomposition occurring in the insulating liquid, for varying the operative conditions of said circuit.

3. Protective system for liquid-insulated electric apparatus comprising a container and a supply of insulating liquid surrounding the apparatus tobe protected, a protective circuit and means adapted to be operated by gases formed by decomposition in the insulating liquid, for varying the operative conditions of said circuit.

4. Protective system for liquid-insulated electric apparatus comprising a container and a supply of insulating liquid surround ing the apparatus to be protected, 2. protective circuit and means adapted to be operated by the buoyancy of gaseous products formed in the insulating liquid, for varying the operative conditions of said circuit.

5. Protective system for liquid-insulated apparatus comprising a container for said apparatus, a supply of insulating liquid in said container surrounding said apparatus,

a protective circuit and a contact device immersed in said liquid and adapted to be protective circuit actuated by variations of the physical state of said liquid for varying the operative conditions of said circuit.

6. Protective system for liquid-insulated electric apparatus comprising a container for said apparatus, a supply of insulating liquid in said container surrounding said apparatus, a protective circuit, a hood open on top and a contact device in the opening of said hood immersed in said liquid and adapted 'to be actuated by variations of the physical state of said liquid for varying the operative conditions of said circuit.

7. Protective system for liquid-insulated electric apparatus comprising a container for said apparatus a supply of insulating liquid in said container surrounding said apparatus, a protective circuit comprising a signalliifg device and a contact device immersed in said liquid and adapted to be actuated by variations of the physical state of said liquid for varying the operative conditions of said circuit.

8. A protective system for. liquid insulated electric apparatus comprising a container and a supply of insulating liquid surrounding the apparatus to be protected, and protective means adapted 'to be operated by products of decomposition occurring in the insulating liquid.

9. The method of controlling abnormal conditions of liquid insulated apparatus which comprises aggregating products of decomposition occurring in the insulation due to abnormal conditions and causing such aggregationto vary the operative condition of protective means associated with such aparatus.

10. The method of controlling abnormal conditions of liquid insulated apparatus,

which comprises aggregating products of decomposition occurrlng 1n the insulation due to abnormal conditions and causing such aggregation to vary the operative condition of a protective circuit associated with such apparatus.

11. The method of controlling abnormal conditions of liquid insulated apparatus which comprises aggregating'gases of decomposition occurring in the insulation due to abnormal conditions and causing such gases to vary the operative condition of a associated with such apparatus.

12. The method of controlling abnormal conditions of liquid: insulated apparatus which comprises subjecting buoyant means associated with the apparatus to the buoyant action of products of decomposition occurring in the insulation due to abnormal conditions, and causing such buoyant means to vary the operative condition of'a protective circuit. t

In testimony whereof I afiix my signature.

' MAX BUCHI-IOLZ. 

